Contaminated liquid commonly must be removed from underground cavities. Contaminated materials that were poured on the ground many years ago eventually combine with ground water and collect in underground cavities and must be removed. The cavities are located by drilling exploratory wells at intervals over the site where contaminated cavities may exist and then drilling remediation wells to remove the contaminated deposits located by the exploratory wells. Since many remediation wells must be drilled if drilled vertically, it has been common to employ horizontal or directional drilling in the remediation of contaminated liquid underground deposits. Normally, a directional drilling rig is set up at a first station, which is normally a site displaced from the cavity containing the deposits. Drilling at an angle is effected until the cavity is reached, and then horizontal drilling is employed through the cavity. Angle drilling is again employed until the drill string exits the ground at a second station displaced from the first station. Plastic pipe, such as HDPE plastic pipe, is then pulled back through the bore hole formed by drilling. The HDPE pipe includes a slotted section which extends through the cavity. A pump connected to the pipe draws contaminated liquid out of the cavity and into the pipe through the slotted section. The contaminated liquid is then drawn out of the pipe at one of the stations and disposed of properly. Accordingly, many cavities can be remediated by using directional drilling instead of multiple vertical wells.
The pipe required in remediation is normally supplied in sections of 10-20 feet. These sections are butt welded using known technology as the pipe is pulled through the bore hole. Short sections of pipe have been necessary, since known manufacturing processes have required that slots be cut in the pipe at substantially right angles to the axis of the pipe. Pipe sections with these radial slots are significantly weaker than unslotted pipe, since only the uncut part of the circumference of the pipe is available to resist the pulling forces. Since pulling long lengths of pipe increases the weight of the pipe that must be pulled through the bore hole, only short lengths of pipe could be added at the station from which the pipe was being pulled, even if slotted pipe in longer lengths would have been available. A butt weld is typically employed to connect adjacent pipe sections. However, butt welding is a difficult, time consuming and expensive process, and therefore unless the welder is very skilled a butt weld may undesirably restrict the pipe diameter and/or become a weak link in the pipe.